Fans today are usually driven by electronically commutated motors. A bearing system for the fan wheel without mechanical bearings is desirable in such motors, principally for reasons of service life but also because of bearing noise. This applies in particular to fast-running fans such as those used, for example, to ventilate computer servers.
Arrangements having permanent magnets are known for journaling without mechanical bearings. This is also referred to as a “non-contact bearing system” or as “magnetically journaled drive systems.” There are two types of so-called passive bearings, i.e. bearings that operate without external energy delivery:
Magnetic bearings that are axially stable but radially unstable.
Magnetic bearings that are radially stable but axially unstable.